ERB 412    1/2″    1200mm    9/16″    12.7mm    30mm    1.18kg    5
ERB 415    1500mm    1.55kg    5
ERB 418    1800mm    1.76kg    5
ERB 424    2400mm    2.36kg    5
ERB 112    5/8″    1200mm    5/8″    14.2mm    30mm    1.53kg    5
ERB 115    1500mm    1.88kg    5
ERB 118    1800mm    2.29kg    5
ERB 124    2400mm    3.00kg    5
ERB 130    3000mm    3.79kg    5
ERB 212    3/4″    1200mm    3/4″    17.2mm    35mm    2.19kg    5
ERB 215    1500mm    2.73kg    5
ERB 218    1800mm    3.27kg    5
ERB 224    2400mm    4.35kg    5
ERB 230    3000mm    5.44kg    5

Earth rods and their fittings are used to provide the interface to ground in all soil conditions in order to achieve satisfactory earthing systems in overhead and underground electricity distribution and transmission networks – providing high fault current capacity on low, medium and high voltage substations, towers and power distribution applications.

Convenient to install where the subsoil condition is free from rock and boulders the earth rod or group of copper rods can be surrounded or backfilled using a low resistance earthing material such as Bentonite.

Depending on the corrosive condition and electrical conductivity of the ground condition the earth rod can be specified to achieve safe, reliable and long term earthing protection – the mechanical strength of the rod must withstand the abrasion and stress endured while installing with an electric or pneumatic driving rod hammer; the head of the earth rod should not “mushroom” or spread when driven.

The earth rods, manufactured by AN Wallis, are extendable by design and used with copper couplers to inter-connect several rods to achieve the required driving depth – the rod couplers provide permanent electrical conductivity and the longer copper earth rods access lower resistivity soils at at lower depths.

Vertically driven earth rods are the most effective electrode for use in typically small area substations or when low soil resistivity ground conditions, into which the rod can  where the rod can penetrate, lies beneath a layer of high soil resistivity.

Earth Rods Diameter v Length

A common misconception is that there is a direct and positive correlation between the diameter of earth rod used and the effect on lowering earth resistance readings. Incorrect.

The graph below confirms that the resistance value is only lowered by 9.5% by doubling the diameter of the rod (which means increasing the weight and the cost of the rod by approximately 400%). Thus the rationale is: use the most economical earth rod that soil conditions will permit the installer to drive.

Rule of thumb – doubling the radius of the earth rod will reduce resistance by approximately 10% and is not a cost-effective option. Doubling the rod length however will theoretically reduce resistance by 40%.